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Ehf extremely high frequency waves appear in the frequency spectrum ? [ Multiple protocol ]

Question 176-1 : 30 ghz 300 ghz 30 mhz 300 mhz 3 mhz 30 mhz 3 ghz 30 ghz

Admin . 1682 exemple 276 30 ghz - 300 ghz30 ghz - 300 ghz

Frequency is defined as the ?

Question 176-2 : Number of cycles occurring in one second in a radio wave expressed in hertz hz maximum deflection in a radio wave expressed in hertz hz minimum number of cycles occurring in one minute in a radio wave expressed in hertz hz length of a radio wave expressed as an angle

Admin .a cycle is any complete round or series of occurrences that repeats or is repeated . 2549.the frequency is the number of cycles occurring in one second in a radio wave expressed in hertz hz exemple 280 Number of cycles occurring in one second in a radio wave expressed in hertz (hz).Number of cycles occurring in one second in a radio wave expressed in hertz (hz).

Which statement about vhf/uhf frequencies is correct ?

Question 176-3 : For both vhf/uhf propagation the space wave is the only propagation path of practical use there is no sky wave under normal conditions vhf has under normal conditions a sky wave wherease uhf has not for both vhf/uhf propagation the space wave is the main propagation path vhf frequencies below 120 mhz may be subjected to sporadic e reflection and then have a sky wave for both vhf/uhf the surface wave is the main propagation path of practical use neither vhf/uhf has a sky wave under any conditions for vhf the surface wave is the main propagation path and for the uhf the space wave

Admin .radio waves in vhf uhf shf and ehf propagate as space waves .radio waves in vlf lf mf and hf propagate as surface/ground waves and sky waves exemple 284 For both vhf/uhf propagation, the space wave is the only propagation path of practical use. there is no sky wave under normal conditions.For both vhf/uhf propagation, the space wave is the only propagation path of practical use. there is no sky wave under normal conditions.

Diffraction is the process by which ?

Question 176-4 : Radio wave travel over and around obstacles a space wave penetrates the ionosphere a ground wave is attenuated over rough ground a direct wave is bent around the form of the earth

Admin .diffraction is the phenomenon by which wave energy bends around an object exemple 288 Radio wave travel over and around obstacles.Radio wave travel over and around obstacles.

Antennas .an ac will be induced ?

Question 176-5 : In a wire parallel to a wire fed with an ac but remote from it in a wire perpendicular to the wire fed with an ac but remote from it in a wire parallel to the wire fed with a dc but remote from it in a wire connected in series to a wire fed with a dc

Admin .inductive coupling refers to the phenomenon that exists when a magnetic field created by an electrical current induces an effect on something else when this happens the two then become mutually reactive or coupled by the inductive effects of the magnetic field for example when an electrical current passes through a wire the electromagnetic field created can induce an electrical current in another wire causing the two to be inductively coupled the principles and effects of inductive coupling find use in devices such as transformers and electric motors .the effects of inductive coupling can be used in one of three primary ways first the inducing field can create a specifically desired electrical current such as in transformers second the inducing field can create a specifically desired mechanical effect such as in electric motors finally the inducing field can create a resonance which itself can create specifically desired electrical currents such as in radio transmission and reception and non contact charging devices .in transformers an electrical current conducts through a wire wound around a core of some type called the primary winding this wire is intentionally placed near another wire wound around the same core called the secondary winding .the electromagnetic field created by passing current through the primary winding then induces an electrical current in the secondary winding .resonant devices work in a way similar to transformers though without the paired windings in these devices a standing electromagnetic field is created when this field encounters an antenna the effect of inductive coupling causes the antenna to resonate which in turn induces an electrical current at its feed point in the case of a radio the induced current is amplified and heard over the radio in a charging device the induced current is directly applied to a battery's terminals to recharge it exemple 292 In a wire, parallel to a wire fed with an ac, but remote from it.In a wire, parallel to a wire fed with an ac, but remote from it.

In aviation the reflection on ionosphere layers phenomenon is used in the ?

Question 176-6 : Hf uhf vlf vhf

Admin .hf radio communications is dependent for most of its applications on the use of the ionosphere this region in the atmosphere enables radio communications signals to be reflected or more correctly refracted back to earth so that they can travel over great distances around the globe ionospheric propagation is normally though of as an hf propagation mode although it use can extend above and below the hf portion of the spectrum on many occasions .once a signal passes through the d region it travels on and reaches first the e and next the f regions at the altitude where these regions are found the air density is very much less and this means that when the free electrons are excited by radio signals and vibrate far fewer collisions occur as a result the way in which these regions act is somewhat different the electrons are again set in motion by the radio signal but they tend to re radiate it as the signal is travelling in an area where the density of electrons is increasing the further it progresses into the region the signal is refracted away from the area of higher electron density in the case of hf signals this refraction is often sufficient to bend them back to earth in effect it appears that the region has 'reflected' the signal .the tendency for this 'reflection' is dependent upon the frequency and the angle of incidence exemple 296 Hf.Hf.

The wavelength of a radio signal transmitted at the frequency 118 7 mhz is ?

Question 176-7 : 2 53 m 25 3 m 2 53 cm 25 3 cm

Admin .wavelength meters = speed of light / frequency.wavelength = 300 000 000 / 118 700 000 = 2 53 m exemple 300 2.53 m.2.53 m.

In the propagation of mf waves the phenomenon of fading is particularly found ?

Question 176-8 : At night due to the combination of the sky and ground waves by day due to the combination of sky and ground waves at night and when raining by day and when raining

Admin .fading when a receiver picks up the sky signal and the surface signal the signals will interfere with each other causing the signals to be cancelled out exemple 304 At night, due to the combination of the sky and ground waves.At night, due to the combination of the sky and ground waves.

A radio signal looses strength as range from the transmitter increases this is ?

Question 176-9 : Attenuation refraction propagation ducting

Admin .attenuation as any radio wave travels away from the transmitter it becomes weaker looses power or is attenuated this results from the rf signal inducing currents into the surface of the earth a good conducting surface such as water will give the signal back with little loss of energy a poor conductive surface such as a hot desert will simply absorb the energy the degree of surface attenuation also varies directly with frequency .there are two main reasons for attenuation . the spreading of available rf energy over a greater area . rf energy is absorbed by the earth atmosphere or ionized layers exemple 308 Attenuation.Attenuation.

Skip distance is the ?

Question 176-10 : Range from the transmitter to the first sky wave highest critical frequency distance wavelength distance of a certain frequency thickness of the ionosphere

Admin .skip distance is the distance between the transmitter and the point on the surface of the earth where the first sky return arrives exemple 312 Range from the transmitter to the first sky wave.Range from the transmitter to the first sky wave.

The wavelength of a radio transmitted on frequency 121 95 mhz is ?

Question 176-11 : 2 46 m 24 60 cm 2 46 cm 24 60 m

Admin .wavelength meters = speed of light / frequency.wavelength = 300 000 000 / 121 950 000 = 2 46 m exemple 316 2.46 m.2.46 m.

What describes polarization ?

Question 176-12 : Orientation of the plane of oscillation of the electrical component of the electromagnetic wave orientation of the antenna to the north pole orientation of the plane of oscillation of the magnetic component of the electromagnetic wave rotation of the antenna around a fixed axis

Admin . polarisation electromagnetic radiation is comprised of the e and h fields which stand for electric and magnetic respectively .the electric field arises from voltage and the magnetic on from current the two act at rightangles to each other . 2552.a wave's polarisation is noted with reference to the electrical field so a vertically polarised wave has a vertical electrical field wich will come from a vertical aerial for efficiency the receiver must have the same orientation . 2553.the shape traced out in a fixed plane by the electric vector as such a plane wave passes over it is a description of the polarization state the following figures show some examples of the evolution of the electric field vector black with time the vertical axes at a particular point in space along with its x and y components red/left and blue/right and the path traced by the tip of the vector in the plane purple the same evolution would occur when looking at the electric field at a particular time while evolving the point in space along the direction opposite to propagation . in linear polarisation the plane of oscillation is fixed in space whereas in circular or eliptical polarisation the plane is rotating exemple 320 Orientation of the plane of oscillation of the electrical component of the electromagnetic wave.Orientation of the plane of oscillation of the electrical component of the electromagnetic wave.

On which bearings errors caused by the shoreline/coastal effect reach their ?

Question 176-13 : Bearings 000° 030° degrees to the coastline bearings 030° 060° degrees to the coastline bearings perpendicular to the coastline any bearings in hf band

Coastal refraction or shoreline effect .low frequency radio waves will refract or bend near a shoreline especially if they are close to parallel to it .least when bearings normal to coastline . radio waves passing the coastline at small angles suffer refraction due to different conducting and reflecting properties over land and sea a false bearing indication is obtained at aircraft flying over sea and taking bearings from ndb located over land the effect is less for an ndb on coast than one inland and on a bearing 90° to coastline then at an oblique angle hence given the choice use beacon at coast and rely on bearings perpendicular to the coastline . 2554 exemple 324 Bearings 000°-030° degrees to the coastline.Bearings 000°-030° degrees to the coastline.

The doppler effect onto the radio signals is ?

Question 176-14 : The shift of frequency of the wave due to the relative movement between the transmitter and the receiver increasing or decreasing of the emitting aircraft ground speed the interference between the direct wave and that reflected by the ground the fluctuation of their propagation velocity

exemple 328 The shift of frequency of the wave due to the relative movement between the transmitter and the receiver.The shift of frequency of the wave due to the relative movement between the transmitter and the receiver.

The d layer and e layer of the atmosphere are part of the ?

Question 176-15 : Ionosphere troposphere tropopause stratosphere

Admin . 2551.the ionosphere is the ionized component of the earth's upper atmosphere from 60 to 400 km above the surface which is vertically structured in three regions or layers d e and f exemple 332 Ionosphere.Ionosphere.

When raising the frequency of an electromagnetic wave the ?

Question 176-16 : Wavelength decreases wavelength and amplitude increases wavelength remains the same wavelength increases

Admin .the relationship between wavelength and frequency is .wavelength = speed of light / frequency.if frequency increases wavelength decreases exemple 336 Wavelength decreases.Wavelength decreases.

The phenomenon when a wave bends when it passes around an impenetrable obstacle ?

Question 176-17 : Diffraction attenuation refraction propagation

Admin .diffraction is the phenomenon by which wave energy bends around an object exemple 340 Diffraction.Diffraction.

The phenomenon of a change in direction of an radio wave em wave occurring due ?

Question 176-18 : Refraction absorption diffraction attenuation

Admin .refraction is the process by which a signal's propagation path bends and the signal changes its speed as it moves from one medium to another different density of the mediums generally the rf energy travels in straight line = following great circle paths however in some cases when there is a change in certain factors the signal's path may change direction the actual extent of the signal's path change varies significantly with the change of the environment .there are 3 main types of refraction .a coastal = the path of rf signal may change as it crosses a coastline .b atmospheric especially low altitude = changes in the path of rf signal may be caused by the changes in temperature pressure or humidity .c ionospheric = paths of rf signals may change as they pass through ionized layers exemple 344 Refraction.Refraction.

A reason that gps satellites use helical antennae is ?

Question 176-19 : That the signal has a circular polarization that the signal has a linear polarization the reduced size of the antennae the reduced weight of the antennae

Admin .helix antennas also commonly called helical antennas have a very distinctive shape as can be seen in the following picture . 2555.a helical antenna is an antenna consisting of a conducting wire wound in the form of a helix in most cases helical antennas are mounted over a ground plane exemple 348 That the signal has a circular polarization.That the signal has a circular polarization.

The mix of an electromagnetic wave with another is called ?

Question 176-20 : Interference reflection diffraction refraction

Admin .interference is a phenomenon in which two waves superimpose to form a resultant wave of greater or lower amplitude interference usually refers to the interaction of waves that are correlated or coherent with each other either because they come from the same source or because they have the same or nearly the same frequency .this question exists also with this statement superposition of two em waves of the same or nearly the same frequency is called interference exemple 352 Interference.Interference.

Speed of a radio wave ?

Question 176-21 : 300 000 km/s 300 000 m/s 300 000 km/h 300 000 m/h

exemple 356 300 000 km/s.300 000 km/s.

For long range ndb's the most common type is ?

Question 176-22 : Lf non a1a mf non a1a mf non a2a lf non a2a

Admin .non a2a bfo off for a2a idents 15 w power 10 25nm range .non a1a bfo on for a1a idents lf non a1a is used for long range exemple 360 Lf, non a1a.Lf, non a1a.

Mountain effect occurring for instance with ndbs is caused by what physical ?

Question 176-23 : Reflection diffraction absorption refraction

Admin .mountain effect mountain areas can cause reflections and to a lesser extent diffractions and lead to the error direction reading by adf .this effect similar to night effect is obtained in mountainous areas where the energy received from an ndb consists of two or more waves one of them direct and others by reflection from the mountains bearing indications are found to change rapidly until the affected area is passed .for information night effect radio waves take two paths to the radio compass receiver the first and normal path is along the earth's surface if only these waves were received the compass would point directly to the ndb the second path is via one or more wave refracting layers above the earth the ionosphere returning to earth to mix with direct waves complete changes in the nature of the waves take place on this path and produce errors in direction exemple 364 Reflection.Reflection.

Which physical effects affecting wave propagation as shown in the figure . 2556 ?

Question 176-24 : A = refraction b = absorption c = reflection a = diffraction b = reflection c = reflection a = absorption b = absorption c = diffraction a = refraction b = attenuation c = interference

exemple 368 A = refraction b = absorption c = reflectionA = refraction b = absorption c = reflection

Which letter in the figure below indicates the 'skip zone' . 2557 ?

Question 176-25 : C d a b

Admin .read carefully skip zone not 'distance' .skip zone dead space is the distance between the limit of the surface wave and the sky wave exemple 372 C.C.

Which letter in the figure below indicates the 'skip distance' . 2557 ?

Question 176-26 : D c a b

Admin .read carefully skip distance not 'zone' .skip distance is the distance between the transmitter and the point on the surface of the earth where the first sky return arrives .it is the range from the transmitter to the first sky wave exemple 376 D.D.

You are flying over sea parallel to the coastline an ndb is situated 10 nm ?

Question 176-27 : Sectors a + b sectors a + d sectors c + d sectors b + d

Admin .coastal refraction or shoreline effect .low frequency radio waves will refract or bend near a shoreline especially if they are close to parallel to it .least when bearings normal perpendicular to coastline .radio waves passing the coastline at small angles suffer refraction due to different conducting and reflecting properties over land and sea a false bearing indication is obtained at aircraft flying over sea and taking bearings from ndb located over land the effect is less for an ndb on coast than one inland and on a bearing 90° to coastline then at an oblique angle hence given the choice use beacon at coast and rely on bearings perpendicular to the coastline exemple 380 Sectors a + bSectors a + b

You are flying parallel to the coastline an ndb is positioned about 10 nm ?

Question 176-28 : Area c + d deflection to the coastline area a + b deflection to the coastline area a + d deflection to the coastline area b + d deflection to the coastline

Admin .coastal refraction or shoreline effect .low frequency radio waves will refract or bend near a shoreline especially if they are close to parallel to it .least when bearings normal perpendicular to coastline ..radio waves passing the coastline at small angles suffer refraction due to different conducting and reflecting properties over land and sea a false bearing indication is obtained at aircraft flying over sea and taking bearings from ndb located over land the effect is less for an ndb on coast than one inland and on a bearing 90° to coastline then at an oblique angle hence given the choice use beacon at coast and rely on bearings perpendicular to the coastline exemple 384 Area c + d, deflection to the coastline.Area c + d, deflection to the coastline.

The phenomenon of a change in direction of an em wave occurring at an interface ?

Question 176-29 : Reflection diffraction absorption refraction

Ecqb03 august 2016 exemple 388 Reflection.Reflection.

What is required to enable an antenna to transmit an electromagnetic wave ?

Question 176-30 : The antenna has to be fed with an alternating current of high frequency the antenna mast must be normal to the ground the antenna has to be fed with a direct current of high frequency the antenna has to be fed with a direct current of low frequency

Ecqb03 august 2016 exemple 392 The antenna has to be fed with an alternating current of high frequency.The antenna has to be fed with an alternating current of high frequency.

An electromagnetic wave has two types of energy field ?

Question 176-31 : An e electrical field and h magnetic field an h electrical field and an e magnetic field a z electrical field and an h magnetic field a z magnetic field and an e electrical field

Admin .an electromagnetic wave consists of an oscillating electric field e and an oscillating magnetic field h which propagates at the speed of light . 2552.the e and h fields are perpendicular to each other exemple 396 An e electrical field and h magnetic field.An e electrical field and h magnetic field.

In aviation electronic systems the so called doppler principle may be used in ?

Question 176-32 : Vor gps and mts and the turbulence mode of awr vor dme and ils vor mti and the mapping mode of awr vor dme and gps

Admin .mts multi spectral targeting system exemple 400 Vor, gps and mts and the turbulence mode of awr.Vor, gps and mts and the turbulence mode of awr.

The wavelength of a radio signal transmitted at the frequency of 3 ghz is ?

Question 176-33 : 10 cm 1 m 1 cm 100 cm

Admin .wavelength in meter = 300 / frequency in mhz.wavelength in meter = 300 000 / frequency in ghz.wavelength = 300 000 / 3 000 000 = 0 1 m exemple 404 10 cm.10 cm.

The phase angle of a wave is ?

Question 176-34 : The fraction of one wavelength expressed in degrees from 000° to 360° the position of a modulation on a wavelength expressed in degrees from 000° to 360° the angle of the modulation on a wavelength expressed in degrees from 000° to 360° the deflection on a wave expressed in degrees from 000° to 360°

exemple 408 The fraction of one wavelength expressed in degrees from 000° to 360°.The fraction of one wavelength expressed in degrees from 000° to 360°.

Wavelength is defined as the ?

Question 176-35 : Physical distance travelled by a radio wave during one cycle of transmission maximum variation of an oscillation distance traveled by a radio wave in one second number of oscillations per second

Admin . 2549 exemple 412 Physical distance travelled by a radio wave during one cycle of transmission.Physical distance travelled by a radio wave during one cycle of transmission.

Antenna .the ils glide path antenna must be located ?

Question 176-36 : At approximately 300 m after the threshold and approximately 120 m laterally from the runway centreline as close as possible from the runway threshold at 150 m after the threshold and about 300 m left from the runway centreline with the localizer antenna 300 m after the threshold in the axis

exemple 416 At approximately 300 m after the threshold and approximately 120 m laterally from the runway centreline.At approximately 300 m after the threshold and approximately 120 m laterally from the runway centreline.

The maximum separation distance between a vor and a dme having the same ?

Question 176-37 : 2000 ft 600 m 600 ft 180 m 60 ft 18 m 200 ft 60 m

exemple 420 2000 ft (600 m).2000 ft (600 m).

The ground wave surface wave propagates as follows ?

Question 176-38 : It travels along the earth' surface and follows the curvature of the earth it is reflected by the ionosphere towards the ground it travels under the ground it is transmitted to the surface of the earth and will be reflected

exemple 424 It travels along the earth' surface and follows the curvature of the earth.It travels along the earth' surface and follows the curvature of the earth.

The sky wave propagates as follows ?

Question 176-39 : A wave transmitted into space will be reflected back to the earth's surface by the ionosphere it travels under the ground it travels along the earth's surface and follows the curvature of the earth a wave transmitted through the air directly from the transmitter to the receiver

Ecqb04 november 2017 exemple 428 A wave transmitted into space will be reflected back to the earth's surface by the ionosphere.A wave transmitted into space will be reflected back to the earth's surface by the ionosphere.

An electromagnetic waves travelling through the air directly from the ?

Question 176-40 : Space wave sky wave ground wave air wave

Ecqb04 november 2017 exemple 432 Space wave.Space wave.

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